But if we allow people to say, spraypaint each other rides - now that is something that will breed a bit of RP - need to get this cleaned at a professional place - but also until you can find that person you can drive this at a bit of a rep hit.
I +1 this as an interesting, completely not abusive or game breaking idea that seems like it should already exist. We let you pin photos to walls and flyers on bar. Business cards slipped onto a vehicle (and I see no reason why this couldn't be limited to 1 card or a small number) could cause good RP. Grief enemies with "I know what you did" or "Call me we got biz -Prog-" by dropping cards or letters or flyers on vehicles is very interesting.
Best original idea I've seen in a while.